1. Field of the Invention
The present invention relates to a customer tray storing apparatus for storing customer trays (known also as universal tray) used in a semiconductor device testing apparatus, and particularly to a customer tray storing apparatus having a pivotally mounted door, the arrangement being such that when the door is opened, it may be rotated or pivoted to a position in which the door is flush with the plane of the bottom surface of the customer tray storing apparatus.
2. Description of the Related Art
In a semiconductor device testing apparatus for testing various types of semiconductor devices, a number of customer trays for accommodating devices to be tested and tested devices are used. Before proceeding to describe the conventional customer tray storing apparatus, the IC testing apparatus for testing a semiconductor integrated circuit (as will be referred to as IC hereinafter) which is typical of semiconductor devices will be briefly described with reference to FIG. 6.
Many of IC testing apparatuses for measuring the electrical characteristics of ICs to be tested (ICs under test) by applying a test signal of a predetermined pattern to the ICs have an IC transporting/handling or processing apparatus (commonly called handler in this art) integrally connected thereto for transporting ICs to be tested to a test or testing section where they are brought into electrical contact with an IC socket mounted on a test head (a part of the IC testing apparatus for supplying and receiving various electrical signals for testing), followed by, after completion of the test, carrying the tested ICs out of the test section and sorting them out into defectless or conforming (pass) and defective or non-conforming (failure) articles on the basis of the test results. In the following disclosure, the present invention will be described by taking the IC testing apparatus having this type of handler connected thereto by way of example for the convenience of explanation.
FIG. 6 is a plan view illustrating the general construction of the IC transporting/handling apparatus (hereinafter referred to as handler) integrally connected to the IC testing apparatus with a plurality of test trays 14 within a soak chamber 22 and an exit chamber 23 and stacked customer trays 13 shown in a perspective view. In addition to a constant temperature chamber 20 containing the soak chamber 22 and a test section 21 therein, and the exit chamber 23 (also called heat-removal/cold-removal chamber), the illustrated handler includes a loader section 11 where ICs to be tested (ICs under test) are transferred from the customer trays and reloaded onto test trays 14, an unloader section 12 where the tested ICs which have been carried on the test tray 14 out through the exit chamber 23 subsequently to undergoing a test in the test section 21 are transferred from the test tray 14 to the customer tray 13 (also called universal tray) to be reloaded on the latter, customer tray storing apparatuses (called customer tray stocker in this field) 4, 4E for storing customer trays 13 loaded with ICs to be tested (ICs under test), customer trays 13 loaded with ICs already tested and sorted, and empty customer trays loaded with no ICs.
The soak chamber 22 of the constant temperature chamber 20 is designed for imposing a temperature stress of either a predetermined high or low temperature on ICs under test loaded on a test tray 14 in the loader section 11 while the test section 21 of the constant temperature chamber 20 is designed for executing electrical tests on the ICs under the predetermined temperature stress imposed in the soak chamber 22. In order to maintain the ICs applied in the soak chamber with a temperature stress of either a predetermined high or low temperature in that temperature during the test, the soak chamber 22 and the test section 21 are both contained in the constant temperature chamber 20 capable of maintaining the interior atmosphere at a predetermined constant temperature.
The illustrated handler is configured such that the soak chamber 22 and the test section 21 of the constant temperature chamber 20 and the exit chamber 23 are arranged in the order named from left to right as viewed in the drawing (referred to as X-axis direction herein) while the loader section 11 and the unloader section 12 are located in front of the constant temperature chamber 20 and the exit chamber 23 (downward in the upward-downward direction as viewed in the drawing (referred to as Y-axis direction herein) which is perpendicular to the X-axis direction). As is apparent from FIG. 6, the loader section 11 is located in front of the soak chamber 22 of the constant temperature chamber 20 while the unloader section 12 is located in front of the test section 21 and the exit chamber 23.
The test tray 14 is moved in a circulating manner from and back to the loader section 11 sequentially through the soak chamber 22 and the test section 21 in the constant temperature chamber 20, the exit chamber 23, and the unloader section 12. In this path of circulating travel, there are disposed a predetermined number of test trays 14 which are successively moved in the directions as indicated by thick solid arrows in FIG. 6 by a test tray transport means, not shown.
A test tray 14 having ICs to be tested loaded thereon from a customer tray 13 in the loader section 11 is conveyed from the loader section 11 to the constant temperature chamber 20, and then delivered to the soak chamber 22 through an inlet port formed in the front wall of the constant temperature chamber 20. The soak chamber 22 is equipped with a vertical transport mechanism which is configured to support a plurality of (say, five) test trays 14 in the form of a stack with a predetermined spacing between stacked two succeeding test trays. In the illustrated example, a test tray newly received from the loader section 11 is supported at the top of the stack while the lowermost test tray is delivered to the test section 21 which on the right-hand side in the X-axis direction, adjoins and communicates with the lower portion of the soak chamber 22. It is thus to be appreciated that test trays 14 are delivered out in the direction perpendicular to that in which they have been introduced.
ICs to be tested are loaded with either a predetermined high or low temperature stress as the associated test tray 14 is moved sequentially from the top to the bottom of the stack by vertically (which is referred to as Z-axis direction) downward movement of the vertical transport mechanism and during a waiting period until the test section 21 is emptied. In the test section 21 there is located a test head, not shown. The test tray 14 which has been carried one by one out of the soak chamber 22 is placed onto the test head where a predetermined number of ICs out of the ICs to be tested loaded on the test tray are brought, as loaded on the test tray, into electrical contact with IC sockets (not shown) mounted on the test head. Upon completion of the test on all of the ICs placed on one test tray through the test head, the test tray 14 is conveyed to the right side in the X-axis direction to the exit chamber 23 where the tested ICs are relieved of heat or cold.
Like the soak chamber 22 as described above, the exit chamber 23 is also equipped with a vertical transport mechanism adapted to support a plurality of (say, five) test trays 14 stacked one on another with a predetermined spacing between stacked two succeeding test trays. In the illustrated example, a test tray newly received from the test section 21 is supported at the bottom of the stack while the uppermost test tray is discharged to the unloader section 12. The tested ICs are relieved of heat or cold to be restored to the outside temperature (room temperature) as the associated test tray 14 is moved sequentially from the bottom to the top of the stack by vertically upward movement of the vertical transport mechanism.
Since the IC test is typically conducted on ICs having a desired temperature stress in a wide range of temperatures such as from -55.degree. C. to +125.degree. C. imposed thereon in the soak chamber 22, the exit chamber 23 cools the ICs with forced air down to the room temperature if the ICs have had a high temperature of, say, about 120.degree. C. applied thereto in the soak chamber 22. if ICs have had a low temperature of, say, about -30.degree. C. applied thereto in the soak chamber 22, the exit chamber 23 heats them with heated air or a heater up to a temperature at which no condensation occurs. For test trays it is usual to use test trays formed of material capable of withstanding such a wide range of temperatures, that is, high/low temperatures. For the application where ICs are tested at the room temperature, however, the test tray 14 need not be formed of material capable of withstanding high/low temperatures.
After the heat removal or cold removal process, the test tray 14 is conveyed from the exit chamber 23 to the unloader section 12 in the direction (facing on the front of the exit chamber 23) perpendicular to that in which it has been introduced from the test section 21 prior to being discharged.
The unloader section 12 is configured to sort out tested ICs by categories based on the data of the test results and load them on the corresponding customer trays 13. In this example, the unloader section 12 provides for stopping the test tray 14 at two positions A and B. The ICs on the test trays 14 stopped at the first position A and the second position B are sorted out based on the data of the test results and transferred onto and stored in the customer trays 13 of the corresponding categories at rest at the customer tray set positions (stop positions) 15, in four customer trays "a" through "d" in the example illustrated.
The test tray 14 emptied in the unloader section 12 is delivered back to the loader section 11 where ICs to be tested are again transferred thereto from the customer tray 13 and loaded thereon to repeat the same steps of operation.
In this example, as shown diagrammatically in FIG. 6, the IC transport assembly for transferring ICs from the customer tray 13 to the test tray 14 in the loader section 11 is in the form of X-Y transport assembly 33 comprising two parallel fixed rails 31 (only the left end one of which is shown) installed over the loader section 11 at the left and right ends thereof respectively and extending in the Y-axis direction (upward-to-downward direction as viewed in the drawing), a movable X-axis arm 32 extending in the X-axis direction (left-to-right direction as viewed in the drawing) which spans between the two rails 31 and is supported at opposite ends thereof by the two rails 31 for movement in the Y-axis direction, and a movable head, not shown (which is known in the art concerned as pick-and-place head) supported by the X-axis arm 32 for movement in the direction that the movable X-axis arm 32 extends, namely, in the X-axis direction. With this construction, the movable head is reciprocally movable in the Y-axis direction between the test tray 14 and the customer tray 13 as well as in the X-axis direction along the movable X-axis arm 32.
The movable head has an IC pick-up pad (IC grasping member) vertically movably mounted on its bottom surface. The movement of the movable head in the X- and Y-axis directions and the downward movement of the pick-up pad bring the pick-up pad into abutment with the ICs placed on the customer tray 13 at rest at the customer tray set position 15 to attract and grasp them by vacuum suction for transfer from the customer tray 13 to the test tray 14. The movable head may be provided with a plurality of, say, eight pick-up pads so that eight ICs at a time may be transferred from the customer tray 13 to the test tray 14.
It is to be noted that a position corrector 24 called "preciser" for correcting the orientation or position of an IC is located between the customer tray set position 15 and the stop position for the test tray 14. The IC position corrector or preciser 24 includes relatively deep recesses into which ICs as being attracted against the pick-up pads are released to fall down prior to being transferred to the test tray 14. The recesses are each bounded by vertical tapered side walls which prescribe for the depth to which the ICs drop into the recesses by virtue of the tapering. Once eight ICs have been positioned relative to each other by the position corrector 24, those accurately positioned ICs are again attracted against the pick-up pads and transferred to the test tray 14. The reason for providing the position corrector 24 is as follows. The customer tray 13 is provided with recesses for holding ICs which are oversized as compared to the size of ICs, resulting in wide variations in positions of ICs stored in the customer tray 13. Consequently, if the ICs as such were grasped by the pick-up pads and transferred directly to the test tray 14, there might be some of them which could not be successfully deposited into the IC storage recesses in the test tray 14. For this reason, the position corrector 24 is disposed which acts to match the accuracy in the array of ICs to that in the array of the IC storage recesses formed in the test tray 14.
The unloader section 12 is equipped with an X-Y transport assembly 34 which is identical in construction to the X-Y transport assembly 33 provided for the loader section 11. The X-Y transport assembly 34 is mounted spanning the first position A and the second position B and performs to transship the tested ICs from the test tray 14 delivered out to the unloader section 12 onto the corresponding customer tray 13. The X-Y transport assembly 34 comprises two parallel fixed rails 35 (only the right end one of which is shown) installed over the unloader section 12 at the ends thereof and extending in the Y-axis direction, a movable X-axis arm 36 extending in the X-axis direction which spans between the two rails 35 and is supported at opposite ends thereof by the two rails 35 for movement in the Y-axis direction, and a movable head (pick-and-place head), not shown, mounted on the movable X-axis arm 36 for movement in the direction that the movable X-axis arm 36 extends, namely, in the X-axis direction.
The sorting operation in the unloader section 12 will now be described. In the IC testing apparatus shown in FIG. 6, the operation of sorting and transshipping tested ICs is performed with respect to only customer trays arranged adjacent to each of the stop positions. Specifically, arranged at the first position A are two right-hand customer trays "a" and "b". Let it be assumed that classification categories 1 and 2 are assigned to the customer trays "a" and "b", respectively. While the test tray 14 is at rest at the first position A, only the tested ICs belonging to the categories 1 and 2 are picked up from the test tray and transferred onto the corresponding customer trays "a" and "b", respectively. Once the test tray 14 at rest at the first position A has been depleted of the ICs belonging to the categories 1 and 2, the test tray is moved to the second position B.
Arranged adjacent to the second position B are two left-hand customer trays "c" and "d". Assuming that classification categories 3 and 4 are allotted to these customer trays "c" and "d", respectively, the tested ICs belonging to the categories 3 and 4 are picked up from the test tray 14 held at the second position B, and transferred onto the corresponding customer trays "c" and "d", respectively. While the sorting is being carried out at the second position B, the next test tray 14 is delivered from the exit chamber 23 to the unloader section 12 and is stopped at the first position A in preparation for the sorting operation.
With the arrangement described above in which the X-Y transport assembly 34 is shared by the two unloader sections (represented by the first and second positions A and B) and in which the sorting operations are limited to the customer trays "a", "b" and customer trays "c", "d" closest to the test tray stop positions A and B, respectively, the distance for the X-Y transport assembly 34 required to travel for the sorting operation can be reduced. It is thus to be understood that this construction permits the overall processing time required for the sorting to be shortened, despite the fact that the single X-Y transport assembly 34 is used for the sorting operation.
It should be noted here that the number of customer trays 13 that can be installed at the customer tray set positions 15 in the unloader section 12 is limited to four in this example by the space available. Hence, the number of categories into which ICs can be sorted in real time operation is limited to four categories 1 to 4 as noted above. While four categories would generally be sufficient to cover three categories for sub classifying "conforming articles" into high, medium and low response speed elements in addition to one category allotted to "non-conforming article," in some instances there may be some among the tested ICs which do not belong to any of these categories. Should there be found any tested ICs which should be classified into a category other than the four categories, a customer tray 13 assigned to the additional category should be taken from the customer tray storing apparatus 4E (which will be referred to as customer tray stocker) which is positioned in the right-hand lower corner as viewed in the drawing and be transported into the unloader section 12 to store the ICs of the additional category. In doing that, it would be needed to transport any one of the customer trays positioned in the unloader section 12 to a predetermined customer tray storing apparatus (which will be referred to as customer tray stocker) for storage therein.
If the replacement of the customer trays is effected in the course of the sorting operation, the latter operation would have to be interrupted during the replacement. For this reason, in this example a buffer section 25 is disposed between the stop positions A and B for the test tray 14 and the locations of the customer trays "a"-"d". The buffer section 25 is configured to temporarily keep tested ICs belonging to a category of rare occurrence.
The buffer section 25 may have a capacity of accommodating, say about twenty to thirty ICs and be equipped with a memory portion for storing the category of ICs placed in IC pockets of the buffer section 25. The locations and category of the individual ICs temporarily kept in the buffer section 25 are thus stored in the memory portion. Between the sorting operations or upon the buffer section 25 being filled with ICs, a customer tray for the category to which the ICs kept in the buffer section belong is carried from the customer tray stocker 4E to the unloader section 12 to receive the ICs. It should be noted that ICs temporarily kept in the buffer section 25 may be scattered over a plurality of categories. In that case, it would be required to transport as many customer trays as the number of categories at a time from the customer tray stocker 4E to the unloader section 12.
The illustrated handler includes one IC-to-be-tested customer tray stocker 4 (the lowest left end stocker as viewed in the drawing) for accommodating customer trays 13 loaded with ICs to be tested, a plurality of tested-IC customer tray stockers for accommodating customer trays 13 loaded with ICs tested and sorted out by categories on the basis of the test results, and at least one stocker for accommodating emptied customer trays. While FIG. 6 shows only the customer trays but no stockers except the stockers 4, 4E at the opposite extreme ends, it is to be understood that all of these customer trays are actually stored in stockers. All of the customer tray stockers described above are configured to accommodate customer trays in the form of a stack. It is to be noted that two of the IC-to-be-tested customer tray stocker 4 may be disposed.
The transport of the customer trays described above is effected by a transfer arm (tray transport) 30. Although not shown in FIG. 6, the transfer arm 30 is adapted to be movable over the entire length of the arrangement of stockers (in the X-axis direction), so that the transfer arm 30 may be moved also to a position over the stocker 4E in which empty customer trays are stored in the form of a stack to transport the uppermost empty customer tray from the top of the stack to the customer tray set position in the unloader section 12.
The transfer arm 30 is provided on its undersurface with grasp means for grasping a customer tray. By way of example, the transfer arm 30 is moved to a position overlying the IC-to-be-tested customer tray stocker 4. In that condition, an elevator (not shown) is actuated to lift the customer trays stacked in the stocker, so that the uppermost customer tray as moved up is engaged and grasped by the grasp means of the transfer arm 30. Once the uppermost customer tray 13 loaded with ICs being tested has been transferred to the transfer arm 30, the elevator is lowered to its original position. The transfer arm 30 is then horizontally moved to and stopped at a position underlying the customer tray set position 15 in the loader section 11 where the transfer arm 30 has its grasp means release the customer tray to allow it to drop into an immediately underlying tray receiver (not shown). The transfer arm 30 having the customer tray unloaded therefrom onto the tray receiver is moved out of the loader section 11. In this condition, the elevator (not shown) is moved upward from below the tray receiver having the customer tray placed thereon to lift up the tray receiver and hence the customer tray loaded with ICs to be tested so that the customer tray is held at the customer tray set position 15.
In the unloader section 12 as well, like the loader section 11, four empty customer trays are positioned and held at the respective customer tray set positions 15 by the transfer arm 30, the tray receivers and associated elevators as described above. Once one customer tray has been fully filled, the customer tray is lowered from the tray set position 15 by the elevator, and is subsequently stored in the customer tray stocker belonging to the category assigned to that particular tray by the transfer arm 30.
A specific example of the conventional customer tray stocker will now be described with reference to FIG. 7. Since all of the stockers are of the same structure, FIG. 7 representatively shows an IC-to-be-tested customer tray stocker 4. As shown, the customer tray stocker 4 comprises a bottom frame or tray supporting frame 41 generally rectangular in plan view and having a rectangular opening 411 in the center thereof for passage of an elevator therethrough. Guide pins 42 are firmly secured to the bottom frame 41 at its four corners and extend upwardly therefrom perpendicularly to the plane of bottom frame. In the illustrated example, each of the guide pins 42 is firmly secured to the bottom frame 41 by passing a bolt 421 through a through-aperture in the bottom frame 41 from therebelow into threaded engagement with axial screw threads formed in the bottom end of the guide pin.
Two guide pins 42 are disposed along each major side of the bottom frame 41 one adjacent each of the opposite ends of the major side while one guide pin 42 is disposed along each minor side of the bottom frame adjacent only one of the opposite ends with the two guide pins at the minor sides longitudinally opposing each other. It is thus seen that no guide pins are attached to the minor sides adjacent the other ends of the minor sides longitudinally opposing each other. In the illustrated example, one guide pin 42 is disposed adjacent one end of each minor side toward the opposite ends of the left-hand major side as viewed in the drawing.
The points of attachment of and the spacings between the guide pins 42 attached adjacent the opposite ends of one of the major sides of the bottom frame 41 and the associated adjacent guide pins 42 on the minor side are determined such that the corners of a customer tray 13 on one of its major sides may enter into the gaps between the associated paired guide pins 42. It is also to be noted that the guide pins along the opposite major sides are located at opposed positions. When a customer tray 13 is stored in the stocker of the construction described above, the corners of the customer tray 13 on one of its major sides will enter into the gaps between the respective paired guide pins 42 whereby the customer tray 13 may be allowed to move only toward the other major side of the bottom frame 41 with respect to the movement in the horizontal direction. However, since there is one guide pin adjacent each of the opposite ends of the other major side of the bottom frame 41, the movement of the customer tray 13 toward the other major side of the bottom frame 41 is also prohibited. It is thus to be appreciated that the customer tray 13 is stored in a stable state in which it is not allowed to move in any direction as far as the movement in the horizontal plane is concerned.
It is to be noted here that cut-outs formed in the middle of the opposite major sides of the bottom frame 41 are to receive operator's hands (fingers) to thereby improve easiness to manipulate when storing customer trays 13 into the stocker or lifting customer trays therefrom.
The customer tray 13 contains a number of ICs 5 arrayed in a matrix. As shown in FIG. 7, a predetermined number of customer trays 13 each loaded with ICs are stored in the IC-to-be-tested customer tray stocker 4 usually in the form of a stack.
When storing a plurality of customer trays 13 in a stack into the stocker, the operator holds and lowers the stack by grasping the lowermost customer tray while guiding the stack along the guide pins 42 upstanding from the four corners of the bottom frame 41. In doing that, although there would be no special difficulty involved if the operator grasps and lowers the customer trays each loaded with ICs one by one into the stocker, it would disadvantageously require a longer time and lower the operating efficiency. For this reason, it is a usual practice to stack a predetermined number of customer trays to be stored one on another and for the operator to hold and lower the stack into the stocker by grasping the lowermost customer tray by hand while guiding the stack along the guide pins 42 from above the stocker.
However, since a plurality of customer trays each loaded with ICs weighs in total as much as 3 to 5 Kg, it is a considerably heavy work for the operator to carry out the storing job. Neither is it always an easy work to grasp a heavy stack of customer trays by hand and guide it along the guide pins 42 from above the stocker 4. In addition, as the stack of customer trays is lowered into the stocker while being in sliding contact with the guide pins 42, there may occur some shock due to frictional interference between the pins 42 and the customer trays, resulting in an accident that some of the ICs placed in the uppermost customer tray may jump up and become misaligned.
Furthermore, since the conventional customer tray stocker is configured to receive customer trays from above, it had the problem in that it was unable to meet the needs of the user for the front loading system of storing customer trays into the handler (the system of transporting customer trays horizontally into the handler from its front and storing them in a stocker).
When a predetermined number of customer trays loaded with no ICs are to be stored in the form of a stack into an empty customer tray stocker 4E as well, there are again the aforesaid problems involved except the problem that some of the ICs loaded on the tray may become misaligned, the total weight of the stack of trays loaded even with no ICs is close to that of the stack of trays loaded with ICs. Likewise in the case of the stocker for accommodating customer trays sorted out in the unloader section 12, it would be very desirable in terms of the operating efficiency, the labor required, etc. if it is possible to transport the stack of customer trays horizontally forwardly toward the front of the handler to take it out of the stocker.